A 3D printing integrated injector

Abstract

A 3D printed integrated injector, wherein the ignition channel runs through the head cavity A and the head cavity B and is located in the middle; the nozzle A and the nozzle B are integrated into a coaxial structure and are evenly distributed in the circumferential direction outside the ignition channel; wherein the nozzle A includes an inlet hole and a straight channel, the inlet hole is located inside the head cavity A, and at least four inlet holes are evenly distributed along the circumferential direction and connected to the straight channel in the center; the nozzle B is located inside the head cavity B, and includes a flow-equalizing annular cavity, a contraction channel, and an outlet annular seam; the overall external cross-section of the flow-equalizing annular cavity and the contraction channel is frustoconical, and the front end of the contraction channel is an outlet annular seam formed between the side wall of the outlet end of the straight channel of nozzle A and the bottom B, and a mixing zone is formed between the outlet end of the straight channel of nozzle A and the bottom B; the outer wall of the head cavity A and the head cavity B, that is, the annular cavity is formed between the annular wall with the flow-equalizing hole and the outer wall of the cavity, and an inlet is provided on the outer wall of the cavity, and the above-mentioned ignition channel, head cavity A, head cavity B, chamber pressure measurement channel, nozzle A, and nozzle B are formed by 3D integrated printing.

Description

Technical Field

[0001] The present invention relates to a 3D printing integrated injector, which can be used in the fields of aerospace, thermal energy engineering and combustion technology. Background Art

[0002] The injector is a key component of a liquid rocket engine. Its function is to spray fuel and oxidizer into the combustion chamber for atomization, vaporization, mixing, and combustion. The resulting high-temperature, high-pressure combustion gas enters the nozzle and is accelerated and ejected to generate thrust. Liquid rocket engine injectors typically consist of hundreds of nozzles connected to multiple base plates through brazing. These injectors have a large number of parts and welds, and the internal quality and mechanical properties of the brazed seams cannot be directly tested but can only be guaranteed through process engineering. If the brazed seams crack, there is a risk of cross-cavity explosion between the fuel and oxidizer chambers. Furthermore, the machining and assembly accuracy of the matching dimensions of the various parts, as well as welding deformation, can easily lead to deviations in the nozzle gap and setback depth, affecting the consistency of the injection state. Furthermore, a skewed nozzle gap can easily lead to a high local mixing ratio, resulting in risks such as nozzle and panel ablation.

[0003] In addition, in order to obtain the working characteristics of the thrust chamber, it is necessary to measure the thrust chamber pressure, etc. The pressure lead-out pipe connects the combustion chamber and the measuring device. Currently, due to the limitations of structural space, the pressure lead-out pipe usually needs to pass through the fuel chamber and the oxidizer chamber. If the brazing seam of the lead-out pipe cracks, it will cause the risk of cross-cavity explosion in the fuel chamber and the oxidizer chamber. If the weld between the lead-out pipe and the oxidizer collector cracks, there is a risk of explosion caused by contact between the combustion chamber gas and the oxidizer.

[0004] In order to minimize the number of parts and welds and improve product reliability, 3D printing laser selective melting (SLM) technology can be used to integrally process hundreds of nozzles, base plates, etc. In order to improve the internal quality, molding accuracy and product performance requirements of the integrated injector molding, it is extremely important to adopt support-free structure design and strengthen the internal quality design of printed products. Summary of the Invention

[0005] The technical problem solved by the present invention is to overcome the shortcomings of the existing technology and provide a 3D printing integrated injector with a small number of part welds, a support-free structure design, a high internal quality design and high-precision throttling controllable.

[0006] The solution of the present invention is: a 3D printing integrated injector, comprising an ignition channel, a head cavity A, a head cavity B, a chamber pressure measurement channel, a nozzle A, and a nozzle B;

[0007] The ignition channel runs through head cavity A and head cavity B and is located in the middle. Nozzles A and B are integrated into a coaxial structure and are evenly distributed circumferentially outside the ignition channel. Nozzle A includes an inlet hole and a straight channel. The inlet hole is located inside head cavity A. At least four inlet holes are evenly distributed along the circumference and connected to the central straight channel.

[0008] Nozzle B is located inside the head cavity B, and includes a flow-equalizing annular cavity, a contraction channel, and an outlet annular seam; the overall external cross-section of the flow-equalizing annular cavity and the contraction channel is a truncated cone, and the front end of the contraction channel is an outlet annular seam formed between the side wall of the outlet end of the straight channel of nozzle A and the bottom B, and a mixing zone is formed between the outlet end of the straight channel of nozzle A and the bottom B; the outer wall of the head cavity A and the head cavity B, that is, an annular cavity is formed between the annular wall with the flow-equalizing hole and the outer wall of the cavity, and an inlet is provided on the outer wall of the cavity, and the fuel enters the head cavity B through the flow-equalizing hole from the inlet, and then flows through the flow-equalizing annular cavity, the contraction channel, and the outlet annular seam through the inlet hole provided on the flow-equalizing annular cavity to enter the mixing zone; the oxidizer enters the mixing zone from the head cavity A through the inlet hole of nozzle A and the straight channel, mixes with the fuel, and then enters the combustion chamber; the chamber pressure measurement channel connects to the combustion chamber from the bottom B and passes through the head cavity B, avoiding the head cavity A; the above-mentioned ignition channel, head cavity A, head cavity B, chamber pressure measurement channel, nozzle A, and nozzle B are formed by 3D integrated printing.

[0009] Preferably, a multi-layer annular nozzle structure is provided outside the ignition channel, and a plurality of coaxial structures integrated with nozzles A and nozzles B are evenly distributed on each layer of the annular nozzle structure.

[0010] Preferably, the inlet and the inlet hole are both hole structures with a round top and a pointed bottom, and the pointed angle range is 60° to 80°.

[0011] Preferably, the area of ​​the flow-averaging holes on the annular wall decreases linearly within the range of 0-180°, and the area ratio from the inlet near the outer wall of the cavity to the opposite side is 1:0.8.

[0012] Preferably, the width of the annular gap at the outlet of the nozzle B is not less than 0.35 mm, and the ratio of its throttling area to the throttling area of ​​the flow-averaging annular cavity is 10% to 20%.

[0013] Preferably, the included angle of the contraction channel is 60° to 80°, and there is a smooth transition between the contraction channel and the outlet annular gap and the flow-averaging annular cavity.

[0014] Preferably, the throttling area of ​​the straight channel of nozzle A is 2 to 3 times the cross-sectional area of ​​the inlet hole.

[0015] Preferably, the bottom B is a microporous structure panel, which ensures structural strength while achieving effective cooling of the panel through air film cooling.

[0016] Preferably, the microporous structure is a straight through hole of 0.1 to 0.3 mm, or a randomly distributed mesh hole of 0.1 to 0.2 mm.

[0017] Preferably, the chamber pressure measurement channel is an internal channel, attached to or embedded in the annular wall with the flow-averaging hole, and has an inner diameter of 2 to 3 mm.

[0018] The beneficial effects of the present invention compared with the prior art are:

[0019] 1) The use of a 3D-printed integrated injector reduces the welds between the head cavity, nozzle, measuring device, and each bottom, preventing the nozzle ablation problem caused by uneven annular gap of the injector nozzle due to the influence of weld heat input;

[0020] 2) The integrated injector is directly formed using 3D printing without support. While ensuring that the internal structure does not collapse and the dimensional accuracy is controllable, it also improves the uniformity of the flow field distribution in each head cavity of the injector and the uniformity of the outflow from each nozzle, thereby improving combustion efficiency and avoiding problems such as nozzle ablation caused by local high mixing ratios.

[0021] 3) Nozzle B adopts designs such as a uniform flow annular cavity and a contraction channel to effectively reduce ineffective local damage to the nozzle and reduce flow resistance along the nozzle, thereby improving the nozzle's anti-disturbance margin. It also increases the annular injection velocity and improves the combustion stability margin of the thrust chamber.

[0022] 4) The integrated printing of bottom B can improve the connection strength with the nozzle, avoiding problems such as difficulty in later assembly. At the same time, the cooling amount can be adjusted by adjusting the size of the microporous structure to adapt to different products.

[0023] 5) The chamber pressure measurement channel is set based on the spatial trend and is directly led out from cavity B. This channel does not pass through cavity A to avoid ice blockage caused by the combustion chamber gas in the channel being frozen by the heat exchange of the fluid in the low-temperature cavity A. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the structure of a 3D printing integrated injector of the present invention;

[0025] Figure 2 It is a half-section view from another angle of the structure of the present invention.

[0026] In the figure: 1 - head cavity A, 2 - head cavity B, 3 - ignition channel, 4 - chamber pressure measurement channel, 5 - nozzle A, 6 - bottom A, 7 - cavity outer wall, 8 - ring wall with equalizing flow hole, 9 - equalizing flow hole, 10 - nozzle B, 11 - cavity inner wall, 12 - bottom B, 13 - inlet. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the embodiments.

[0028] A 3D printing integrated injector, such as Figure 1As shown, it includes head cavity A1, head cavity B2, ignition channel 3, and chamber pressure measurement channel 4; the ignition channel runs through head cavity A and head cavity B and is located in the middle;

[0029] In the aforementioned integrated 3D printing injector, nozzles A5 and B10 are integrated into a coaxial structure and evenly spaced circumferentially around the ignition channel. Nozzle A comprises an inlet hole and a straight channel. The inlet hole, located within head cavity A1, is a 70° angled, rounded upper and pointed lower hole, ensuring support-free direct 3D printing. At least four inlet holes are evenly spaced circumferentially and connected to the central straight channel. The throttling area of ​​the straight channel of nozzle A is approximately 2.4 times the cross-sectional area of ​​the inlet hole. A mixing zone is formed between the outlet end of the straight channel of nozzle A5 and the bottom B12.

[0030] In the aforementioned integrated 3D printing injector, the nozzle B10, located within the head cavity B2, comprises a flow-equalizing annular cavity, a contraction channel, and an outlet annular slit. This replaces the traditional long annular slit, ensuring a constant pressure drop while maintaining support-free printing while increasing the outlet injection velocity and the gas-liquid injection velocity ratio. It also acts as a damping chamber, reducing instability. The front end of the contraction channel is the outlet annular slit formed between the sidewall of the outlet end of the straight channel of nozzle A5 and the bottom B12. Its width is no less than 0.35 mm, and its throttling area is 15% of the throttling area of ​​the flow-equalizing annular cavity. The contraction channel has a 70° angle, and a smooth transition between the contraction channel, the outlet annular slit, and the flow-equalizing annular cavity.

[0031] In the aforementioned 3D printing integrated injector, the nozzle B10 has a truncated cone-shaped cross section, which ensures direct molding without support during 3D printing and improves the uniformity of the flow field distribution in the gas head cavity.

[0032] In the above-mentioned 3D printing integrated injector, the outer wall of the head cavity A1 and the head cavity B2, that is, the annular wall with the equalizing flow hole and the outer wall of the cavity form an annular cavity, and an inlet is provided on the outer wall of the cavity. The fuel enters the head cavity B2 from the inlet through the equalizing flow hole 9, wherein the equalizing flow holes 9 are symmetrically and evenly distributed on the annular wall with the equalizing flow hole, and are special-shaped holes with a round top and a pointed bottom. The area of ​​the equalizing flow hole decreases linearly within the range of 0-180°, and the area ratio from the vicinity of the inlet 13 to the opposite side is 1:0.8; the fuel then enters the equalizing flow annular cavity, the contraction channel, and the outlet annular seam through the inlet hole provided on the equalizing flow annular cavity of the nozzle B10, and enters the mixing zone; the oxidizer enters the mixing zone from the head cavity A1 through the inlet hole of the nozzle A5 and the straight channel, and is mixed with the fuel before entering the combustion chamber;

[0033] The chamber pressure measurement channel is connected to the combustion chamber from the bottom B12 and only passes through the head cavity B2; the above-mentioned head cavity A1, head cavity B2, ignition channel 3, chamber pressure measurement channel 4, nozzle A5, and nozzle B10 are formed by 3D integrated printing.

[0034] In the above-mentioned 3D printing integrated injector, the bottom B12 is a microporous structure panel, which ensures structural strength while achieving effective cooling of the panel through air film cooling; the microporous structure can be a 0.2mm straight through hole or a randomly distributed 0.15mm mesh.

[0035] In the above-mentioned 3D printed integrated injector, the chamber pressure measurement channel 3 is set based on the spatial trend. It is an internal channel and can be attached or embedded in the ring wall with equal flow holes and directly led out from cavity B. The inner diameter of the chamber pressure measurement channel is usually 2 mm.

[0036] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of protection of the technical solution of the present invention.

[0037] Parts of the present invention that are not described in detail belong to common knowledge among those skilled in the art.

Claims

1. A 3D printing integrated injector, characterized in that: It includes ignition channel, head cavity A, head cavity B, chamber pressure measurement channel, nozzle A, and nozzle B; The ignition channel runs through the head cavity A and the head cavity B and is located in the middle; the nozzle A and the nozzle B are integrated into a coaxial structure and are evenly distributed around the ignition channel; The nozzle A includes an inlet hole and a straight channel. The inlet hole is located inside the head cavity A. At least four inlet holes are evenly distributed along the circumference and connected to the straight channel in the center. Nozzle B is located inside the head cavity B, and includes a flow-equalizing annular cavity, a contraction channel, and an outlet annular seam; the overall external cross-section of the flow-equalizing annular cavity and the contraction channel is a truncated cone, and the front end of the contraction channel is an outlet annular seam formed between the side wall of the outlet end of the straight channel of nozzle A and the bottom B, and a mixing zone is formed between the outlet end of the straight channel of nozzle A and the bottom B; the outer wall of the head cavity A and the head cavity B, that is, an annular cavity is formed between the annular wall with the flow-equalizing hole and the outer wall of the cavity, and an inlet is provided on the outer wall of the cavity, and the fuel enters the head cavity B through the flow-equalizing hole from the inlet, and then flows through the flow-equalizing annular cavity, the contraction channel, and the outlet annular seam through the inlet hole provided on the flow-equalizing annular cavity to enter the mixing zone; the oxidizer enters the mixing zone from the head cavity A through the inlet hole of nozzle A and the straight channel, mixes with the fuel, and then enters the combustion chamber; the chamber pressure measurement channel connects to the combustion chamber from the bottom B and passes through the head cavity B, avoiding the head cavity A; the above-mentioned ignition channel, head cavity A, head cavity B, chamber pressure measurement channel, nozzle A, and nozzle B are formed by 3D integrated printing.

2. The 3D printing integrated injector according to claim 1, characterized in that: A multi-layer annular nozzle structure is arranged outside the ignition channel, and a plurality of coaxial structures integrated by nozzles A and nozzles B are evenly distributed on each layer of the annular nozzle structure.

3. The 3D printing integrated injector according to claim 1, characterized in that: The inlet and the inlet hole are both hole structures with a round top and a pointed bottom, and the pointed angle range is 60° to 80°.

4. The 3D printing integrated injector according to claim 1, characterized in that: The area of ​​the flow-averaging holes on the annular wall decreases linearly within the range of 0-180°, and the area ratio from the inlet near the outer wall of the cavity to the opposite side is 1:0.

8.

5. The 3D printing integrated injector according to claim 1, characterized in that: The width of the annular gap at the outlet of nozzle B is not less than 0.35 mm, and its throttling area is 10% to 20% of the throttling area of ​​the uniform flow annular cavity.

6. The 3D printing integrated injector according to claim 5, characterized in that: The included angle of the contraction channel is 60° to 80°, and there is a smooth transition between the contraction channel, the outlet annular gap and the flow-averaging annular cavity.

7. The 3D printing integrated injector according to claim 1, characterized in that: The throttling area of ​​the straight channel of nozzle A is 2 to 3 times the cross-sectional area of ​​the inlet hole.

8. The 3D printing integrated injector according to claim 1, characterized in that: Bottom B is a microporous structure panel, which ensures structural strength while achieving effective cooling of the panel through air film cooling.

9. The 3D printing integrated injector according to claim 7, characterized in that: The microporous structure is a straight through hole of 0.1 to 0.3 mm, or a randomly distributed mesh of 0.1 to 0.2 mm.

10. The 3D printing integrated injector according to claim 1, characterized in that: The chamber pressure measurement channel is an internal channel, attached to or embedded in the annular wall with a flow-equalizing hole, and its inner diameter is 2 to 3 mm.

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